let watermark = {}
let timeFormate = ()=>{
    let date = new Date();
    let Y = date.getFullYear();
    let M = (date.getMonth()+1)<10 ? '0' + (date.getMonth()+1) : date.getMonth()+1;
    let D = date.getDate() < 10 ? '0' + date.getDate() : date.getDate();
    return Y +''+ M +''+ D
}
const id = '7.432756475.689573874'
let outWatermark = ()=>{
    if (document.getElementById(id) !== null) {
        const div = document.getElementById(id)
        div.style.display = 'none'
     }
}
let setWatermark = (str) => {
 let date = timeFormate();
 if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id));
 }

 

 //创建一个画布
 let can = document.createElement('canvas');
 //设置画布的长宽
 can.width = (document.body.clientWidth - 200) / 4;
 can.height = 420;

 let cans = can.getContext('2d');
 //旋转角度
 cans.rotate(-30 * Math.PI / 180);
 cans.font = '16px Vedana';
 //设置填充绘画的颜色、渐变或者模式
 cans.fillStyle = 'rgba(200, 200, 200, 0.60)';
 //设置文本内容的当前对齐方式
 cans.textAlign = 'left';
 //设置在绘制文本时使用的当前文本基线
 cans.textBaseline = 'Middle';
 //在画布上绘制填色的文本（输出的文本，开始绘制文本的X坐标位置，开始绘制文本的Y坐标位置）
 cans.fillText(str+date, 0, can.height / 2);

 let div = document.createElement('div');
 div.id = id;
 div.style.pointerEvents = 'none';
 div.style.top = '50px';
 div.style.left = '200px';
 div.style.position = 'fixed';
 div.style.zIndex = '2000';
 div.style.width = document.body.clientWidth + 'px';
 div.style.height = document.body.clientHeight + 'px';
 div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat';
 document.body.appendChild(div);
 return id;
}

// 该方法只允许调用一次
watermark.set = (str) => {
 setWatermark(str);
 setInterval(() => {
    if (document.getElementById(id) === null) {
        setWatermark(str);
    }
 }, 500);
 /* window.onresize = () => {
    setWatermark(str);
 }; */
}
watermark.out = () => {
    outWatermark()
   }

export default watermark;